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101.
Luca Pasquini Elsa Callini Matteo Brighi Federico Boscherini Amelia Montone Torben R. Jensen Chiara Maurizio Marco Vittori Antisari Ennio Bonetti 《Journal of nanoparticle research》2011,13(11):5727-5737
We report on the hydrogen storage behaviour of Mg nanoparticles (NPs) (size range 100 nm–1 μm) with metal-oxide core–shell
morphology synthesized by inert gas condensation and decorated by transition metal (TM) (Pd or Ti) clusters via in situ vacuum
deposition. The structure and morphology of the as-prepared and hydrogenated NPs is studied by electron microscopy, X-ray
diffraction including in situ experiments and X-ray absorption spectroscopy, in order to investigate the relationships with
the hydrogen storage kinetics measured by the volumetric Sieverts method. With both Pd and Ti, the decoration deeply improves
the hydrogen sorption properties: previously inert NPs exhibit complete hydrogenation with fast transformation kinetics, good
stability and reversible gravimetric capacity that can attain 6 wt%. In the case of Pd-decoration, the occurrence of Mg–Pd
alloying is observed at high temperatures and in dependence of the hydrogen pressure conditions. These structural transformations
modify both the kinetics and thermodynamics of hydride formation, while Ti-decoration has an effect only on the kinetics.
The experimental results are discussed in relation with key issues such as the amount of decoration, the heat of mixing between
TM and Mg and the binding energy between TM and hydrogen. 相似文献
102.
Aflatoxin M1 determination in cheese by liquid chromatography-tandem mass spectrometry 总被引:1,自引:0,他引:1
Cavaliere C Foglia P Guarino C Marzioni F Nazzari M Samperi R Laganà A 《Journal of chromatography. A》2006,1135(2):135-141
A new method for determining aflatoxin M1 (AFM1) in cheese by liquid chromatography-tandem mass spectrometry has been developed. Two methodologies were compared for sample extraction. The first one involves sample extraction with dichloromethane for hard, aged cheese or acetone for fresh cheese and includes a preliminary matrix solid-phase dispersion-extraction step before solid-phase extraction (SPE) clean-up by a Carbograph-4 cartridge. The second method uses a water/methanol solution (90:10, v/v) extraction at 150 degrees C before clean-up. The average recoveries of AFM1 from samples spiked at levels of 0.25-0.45 microg/kg, were 81-92% and the precision (RSD) ranged from 3 to 7% with the first method, whilst the average recoveries were 79-84%, and RSD ranged from 7 to 15% for the second method. Due to different matrix effect, the quantification limits were 0.019-0.025 microg/kg in the first case and 0.048-0.143 microg/kg in the second one, depending on cheese typology. 相似文献
103.
Costa M Cà ND Gabriele B Massera C Salerno G Soliani M 《The Journal of organic chemistry》2004,69(7):2469-2477
An effective and straightforward approach to the synthesis of 4H-3,1-benzoxazines 3 and 4, quinazolin-2-ones 5, and quinoline-4-one derivatives 6 and 7 is provided by palladium-catalyzed cyclization-alkoxycarbonylation of variously substituted 2-(trimethylsilanyl)ethynylaniline amide or urea derivatives 2. Reactions are carried out in 7:1 MeCN/MeOH at 65 or 75 degrees C in the presence of catalytic amounts of 10% Pd/C in conjunction with Bu(4)NI and KF and under 2.4 MPa of a 3:1 mixture of CO and air. Anti and syn 6-exo-dig cyclization modes account for the formation of the two stereoisomers. Isomerization of the vinylpalladium intermediate may occur as well. Formation of a double carbonylation product 7r and of a gem-dimethoxycarbonylation product 6s, whose structures have been determined by X-ray diffraction analysis, is justified through an unusual type of rearrangement. 相似文献
104.
Dr. Bozheng Sun Dr. Meagan S. Oakley Dr. Kota Yoshida Yanwen Yang Prof. Matteo Tommasini Dr. Chiara Zanchi Dr. Andrea Lucotti Dr. Michael J. Ferguson Dr. Frank Hampel Prof. Mariusz Klobukowski Prof. Rik R. Tykwinski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(38):e202200616
Cyclic tetraaryl[5]cumulenes ( 1 a–f ) have been synthesized and studied as a function of increasing ring strain. The magnitude of ring strain is approximated by the extent of bending of the cumulenic core as assessed by a combination of X-ray crystallographic analysis and DFT calculations. Trends are observed in 13C NMR, UV-vis, and Raman spectra associated with ring strain, but the effects are small. In particular, the experimental HOMO-LUMO gap is not appreciably affected by bending of the [5]cumulene framework from ca. 174° (λmax=504 nm) in 1 a to ca. 178° (λmax=494 nm) in 1 f . 相似文献
105.
Maria Luisa Dalla Chiara 《International Journal of Theoretical Physics》1995,34(8):1331-1336
The event-structure of a state-event system, containing unsharp elements, can be described either as aregular involutive bounded poset, or alternatively as anunsharp orthoalgebra (called alsodifference poset oreffect algebra). Such structures give rise to different forms ofunsharp quantum logics. 相似文献
106.
Cavaliere C Foglia P Guarino C Nazzari M Samperi R Laganà A 《Rapid communications in mass spectrometry : RCM》2007,21(4):550-556
A liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for measurement of aflatoxins B1, B2, G1, and G2 in maize is described. Aflatoxins (AFs) were extracted from 1 g samples by using tri-portions of acetonitrile/water (80:20, v/v) (10 + 7 + 7 mL), and 2/5 of the extract diluted to 500 mL by water was cleaned up with a 100 mg Carbograph-4 cartridge. After the addition of the internal standard AFM1, the final extract was analyzed by LC/ESI-MS/MS in positive ion mode using multiple reaction monitoring with a triple-quadrupole instrument. A C(18) column thermostatted at 45 degrees C with a mobile phase gradient of acetonitrile/water with 2 mmol/L ammonium formate was used. Although the matrix suppression effect was negligible, quantitation was achieved by an external calibration procedure using matrix-matched standard solutions to improve accuracy. Sample recoveries at four spiking levels ranged from 81 to 101% (relative standard deviation (RSD) =12%), and the method quantification limit ranged from 0.1 to 0.6 microg/kg. This method is sensitive, accurate and selective, and can thus be applied as a confirmatory procedure in establishing non-compliance with EU permitted maximum levels (2 microg/kg for aflatoxin B1 and 4 microg/kg for total AFs in corn products). This work also includes an application to samples obtained from retail markets and from experimental trial fields. Of the 48 samples, 15 were found to be contaminated with AFs and, of these, 5 did not comply with European Union legislation (AFB1 =2 microg/kg). 相似文献
107.
Flavio Granato Andrea Bianco Chiara Bertarelli Giuseppe Zerbi 《Macromolecular rapid communications》2009,30(6):453-458
Conductive Polyamide 6 (PA‐6) nanofibers were prepared by making a conductive polypyrrole coating obtained by a polymerization of pyrrole molecules directly on the fiber surface. A solution of PA‐6 added with ferric chloride in formic acid has been electrospun and the fibers obtained showed an average diameter of 260 nm with a smooth surface. The fibers have been then exposed to pyrrole vapours and a compact coating of polypyrrole was formed on the fiber surface. The growth of the coating was monitored by measuring the increment of the fiber diameter and by FT‐IR spectroscopy. The same technique was used to study the interaction between the ferric chloride and the polyamide chains. The polypyrrole coating on the fibers turned out to be conductive with a pure resistive characteristic and the stability of the conductivity was evaluated in air at room temperature.
108.
Spot overlapping in two-dimensional polyacrylamide gel electrophoresis separations: a statistical study of complex protein maps 总被引:1,自引:0,他引:1
A statistical approach able to extract the information contained in a two-dimenisional polyacrylamide gel electrophoresis (2-D PAGE) separation is here reported. The method is based on the quantitative theory of peak overlapping, a procedure previously developed by the authors and here extended to 2-D separations. The whole map is divided into many strips in order to obtain 1-D separations on which the statistic procedure is applied: the developed algorithms, on the basis of spot experimental data (intensity and spatial coordinates) permit to estimate the intrinsic number of components and to single out the specific order present in spot positions. The procedure was validated on computer-simulated maps. Its applicability to real samples was tested on maps obtained from literature sources. The following important information on protein mixtures can be extracted: (i) the number of proteins can be accurately estimated, on the basis of the spatial coordinates and intensities of spots detected in the 2-D PAGE map; (ii) the model describing distribution of interdistance between adjacent spots can be identified in both the separation dimensions; (iii) the presence of repeated interdistances in spot positions in the maps can be easily singled out: these regularities suggest specific protein modifications. 相似文献
109.
Giovanni Ghigo Matteo Bonomo Achille Antenucci Chiara Reviglio Stefano Dughera 《Molecules (Basel, Switzerland)》2022,27(6)
Deep Eutectic Solvent (DES)-like mixtures, based on glycerol and different halide organic and inorganic salts, are successfully exploited as new media in copper-free halodediazoniation of arenediazonium salts. The reactions are carried out in absence of metal-based catalysts, at room temperature and in a short time. Pure target products are obtained without the need for chromatographic separation. The solvents are fully characterized, and a computational study is presented aiming to understand the reaction mechanism. 相似文献
110.